Re: [PATCH v3 27/34] s390/irqflags: Do not instrument arch_local_irq_*() with KMSAN
On Thu, Dec 14, 2023 at 12:24:47AM +0100, Ilya Leoshkevich wrote:
> KMSAN generates the following false positives on s390x:
>
> [6.063666] DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled())
> [ ...]
> [6.577050] Call Trace:
> [6.619637] [<0690d2de>] check_flags+0x1fe/0x210
> [6.665411] ([<0690d2da>] check_flags+0x1fa/0x210)
> [6.707478] [<006cec1a>] lock_acquire+0x2ca/0xce0
> [6.749959] [<069820ea>] _raw_spin_lock_irqsave+0xea/0x190
> [6.794912] [<041fc988>] __stack_depot_save+0x218/0x5b0
> [6.838420] [<0197affe>] __msan_poison_alloca+0xfe/0x1a0
> [6.882985] [<07c5827c>] start_kernel+0x70c/0xd50
> [6.927454] [<00100036>] startup_continue+0x36/0x40
>
> Between trace_hardirqs_on() and `stosm __mask, 3` lockdep thinks that
> interrupts are on, but on the CPU they are still off. KMSAN
> instrumentation takes spinlocks, giving lockdep a chance to see and
> complain about this discrepancy.
>
> KMSAN instrumentation is inserted in order to poison the __mask
> variable. Disable instrumentation in the respective functions. They are
> very small and it's easy to see that no important metadata updates are
> lost because of this.
>
> Signed-off-by: Ilya Leoshkevich
> ---
> arch/s390/include/asm/irqflags.h | 18 +++---
> drivers/s390/char/sclp.c | 2 +-
> 2 files changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/arch/s390/include/asm/irqflags.h
> b/arch/s390/include/asm/irqflags.h
> index 02427b205c11..7353a88b2ae2 100644
> --- a/arch/s390/include/asm/irqflags.h
> +++ b/arch/s390/include/asm/irqflags.h
> @@ -37,12 +37,19 @@ static __always_inline void __arch_local_irq_ssm(unsigned
> long flags)
> asm volatile("ssm %0" : : "Q" (flags) : "memory");
> }
>
> -static __always_inline unsigned long arch_local_save_flags(void)
> +#ifdef CONFIG_KMSAN
> +#define ARCH_LOCAL_IRQ_ATTRIBUTES \
> + noinline notrace __no_sanitize_memory __maybe_unused
> +#else
> +#define ARCH_LOCAL_IRQ_ATTRIBUTES __always_inline
> +#endif
> +
> +static ARCH_LOCAL_IRQ_ATTRIBUTES unsigned long arch_local_save_flags(void)
> {
Please change this to lower case and long single lines, so it matches the
more common patterns:
#ifdef CONFIG_KMSAN
#define __arch_local_irq_attributes noinline notrace __no_sanitize_memory
__maybe_unused
#else
#define __arch_local_irq_attributes __always_inline
#endif
static __arch_local_irq_attributes unsigned long arch_local_save_flags(void)
...
Re: [PATCH v3 27/34] s390/irqflags: Do not instrument arch_local_irq_*() with KMSAN
On Thu, Dec 14, 2023 at 12:36 AM Ilya Leoshkevich wrote: > > KMSAN generates the following false positives on s390x: > > [6.063666] DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled()) > [ ...] > [6.577050] Call Trace: > [6.619637] [<0690d2de>] check_flags+0x1fe/0x210 > [6.665411] ([<0690d2da>] check_flags+0x1fa/0x210) > [6.707478] [<006cec1a>] lock_acquire+0x2ca/0xce0 > [6.749959] [<069820ea>] _raw_spin_lock_irqsave+0xea/0x190 > [6.794912] [<041fc988>] __stack_depot_save+0x218/0x5b0 > [6.838420] [<0197affe>] __msan_poison_alloca+0xfe/0x1a0 > [6.882985] [<07c5827c>] start_kernel+0x70c/0xd50 > [6.927454] [<00100036>] startup_continue+0x36/0x40 > > Between trace_hardirqs_on() and `stosm __mask, 3` lockdep thinks that > interrupts are on, but on the CPU they are still off. KMSAN > instrumentation takes spinlocks, giving lockdep a chance to see and > complain about this discrepancy. > > KMSAN instrumentation is inserted in order to poison the __mask > variable. Disable instrumentation in the respective functions. They are > very small and it's easy to see that no important metadata updates are > lost because of this. > > Signed-off-by: Ilya Leoshkevich Reviewed-by: Alexander Potapenko
[PATCH v3 27/34] s390/irqflags: Do not instrument arch_local_irq_*() with KMSAN
KMSAN generates the following false positives on s390x:
[6.063666] DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled())
[ ...]
[6.577050] Call Trace:
[6.619637] [<0690d2de>] check_flags+0x1fe/0x210
[6.665411] ([<0690d2da>] check_flags+0x1fa/0x210)
[6.707478] [<006cec1a>] lock_acquire+0x2ca/0xce0
[6.749959] [<069820ea>] _raw_spin_lock_irqsave+0xea/0x190
[6.794912] [<041fc988>] __stack_depot_save+0x218/0x5b0
[6.838420] [<0197affe>] __msan_poison_alloca+0xfe/0x1a0
[6.882985] [<07c5827c>] start_kernel+0x70c/0xd50
[6.927454] [<00100036>] startup_continue+0x36/0x40
Between trace_hardirqs_on() and `stosm __mask, 3` lockdep thinks that
interrupts are on, but on the CPU they are still off. KMSAN
instrumentation takes spinlocks, giving lockdep a chance to see and
complain about this discrepancy.
KMSAN instrumentation is inserted in order to poison the __mask
variable. Disable instrumentation in the respective functions. They are
very small and it's easy to see that no important metadata updates are
lost because of this.
Signed-off-by: Ilya Leoshkevich
---
arch/s390/include/asm/irqflags.h | 18 +++---
drivers/s390/char/sclp.c | 2 +-
2 files changed, 16 insertions(+), 4 deletions(-)
diff --git a/arch/s390/include/asm/irqflags.h b/arch/s390/include/asm/irqflags.h
index 02427b205c11..7353a88b2ae2 100644
--- a/arch/s390/include/asm/irqflags.h
+++ b/arch/s390/include/asm/irqflags.h
@@ -37,12 +37,19 @@ static __always_inline void __arch_local_irq_ssm(unsigned
long flags)
asm volatile("ssm %0" : : "Q" (flags) : "memory");
}
-static __always_inline unsigned long arch_local_save_flags(void)
+#ifdef CONFIG_KMSAN
+#define ARCH_LOCAL_IRQ_ATTRIBUTES \
+ noinline notrace __no_sanitize_memory __maybe_unused
+#else
+#define ARCH_LOCAL_IRQ_ATTRIBUTES __always_inline
+#endif
+
+static ARCH_LOCAL_IRQ_ATTRIBUTES unsigned long arch_local_save_flags(void)
{
return __arch_local_irq_stnsm(0xff);
}
-static __always_inline unsigned long arch_local_irq_save(void)
+static ARCH_LOCAL_IRQ_ATTRIBUTES unsigned long arch_local_irq_save(void)
{
return __arch_local_irq_stnsm(0xfc);
}
@@ -52,7 +59,12 @@ static __always_inline void arch_local_irq_disable(void)
arch_local_irq_save();
}
-static __always_inline void arch_local_irq_enable(void)
+static ARCH_LOCAL_IRQ_ATTRIBUTES void arch_local_irq_enable_external(void)
+{
+ __arch_local_irq_stosm(0x01);
+}
+
+static ARCH_LOCAL_IRQ_ATTRIBUTES void arch_local_irq_enable(void)
{
__arch_local_irq_stosm(0x03);
}
diff --git a/drivers/s390/char/sclp.c b/drivers/s390/char/sclp.c
index d53ee34d398f..fb1d9949adca 100644
--- a/drivers/s390/char/sclp.c
+++ b/drivers/s390/char/sclp.c
@@ -736,7 +736,7 @@ sclp_sync_wait(void)
cr0_sync.val = cr0.val & ~CR0_IRQ_SUBCLASS_MASK;
cr0_sync.val |= 1UL << (63 - 54);
local_ctl_load(0, _sync);
- __arch_local_irq_stosm(0x01);
+ arch_local_irq_enable_external();
/* Loop until driver state indicates finished request */
while (sclp_running_state != sclp_running_state_idle) {
/* Check for expired request timer */
--
2.43.0
